Beneficiation of acidic minerals



Patented Jan. 10, 1950 tiNlTED STATES PAT EN'l OFFICE Stamford, and Elmer W. wich, Conn., assignors to Company, New York, N.

Maine No Drawing. Application Gieseke, Old Green- American Cyanamid Y., a corporation of March 10, 1948,

Serial No. 14,155

4 Claims. (Cl. 209-166) The present invention relates to the beneficia-- tion of mineral values of various ores by the use of. a new class of reagents for selectively separating acidic minerals from the other ore constituents. Still more particularly, the present invention relates to a novel process of froth flotation, using as promoters or collectors N-alkylated polyalkylene polyamines and/ or N-alkylated N'- acylated polyamines, the acyl group be ing that of a fatty acid acylating agent. This application constitutes a continution-in-part of our copending application, now abandoned, Serial No. 575,190, filed January 29, 1945, which is a continuation-in-part of its copending application, now abandoned, Serial No. 437,036, filed March 31, 1942.

The present invention is primarily concerned with froth flotation. However, the teachings thereof are also applicable to the separation of acidic minerals by other processes dependent upon surface phenomena. Such processes include film flotation, agglomeration, tabling and other related operations. Similarly, the process is not necessarily limited to the treatment of any particular ore. However, its most important field of use is in the separation by froth flotation of silica and silicate minerals from such nonmetalllc ores as limestone, bauxite, barytes, ilmenite, calcite and the like. In particular, it is very successful in the separation of silicious gangue from phosphate ores. It also finds a considerable utility in the separation of silicious gangue from such oxidized iron ores as hematite, magnetite and the like.

In accordance with this invention, natural or partially processed ores, comprising a mixture of acidic minerals with other mineral constituents are subjected to a separation or concentration process in the presence of a promoter for the acidic ore minerals. The promoter used may be described as an N-alkylated polyalkylene polyamine or a fatty acid acylated derivative of such N-alkylated polyamines. If so desired a mixture of such reagents may be employed.

The reagents of the present invention are effective promoters or collectors for negatively charged or acidic ore materials generally and said acidic material may either .be worthless gangue or valuable ore constituents. The most important uses are, however, in connection with the froth flotation of silica from non-metallic ores in which the silicious gangue may represent aminor proportion of the ore rather than metallie and sulfide ores in which the gangue usually represents the major proportion of the ores. Representative acidic ore materials are the feldspars, quartz, pyroxenes, the spinels, biotite, muscovite, clays and the like.

In the past, a number of reagents have been proposed for similar purposes. Most of them, however, have not been as satisfactory for all purposes as might be desired. Many of them are specific to certain minerals, others are not sumciently available at all times, and still more of them suffer an economic disadvantage due to relatively expensive materials used in their preparation.

Therefore, the principal objects of the present invention are to provide a class of reagents which is readily prepared: which is not necessarily specific to a particular type of ore; which is readily prepared from commonly available materials; which may be used successfully in economic competitionand which exhibits a high degree of selectivity for acidic minerals in the presence of non-metallic minerals. I

In general ithas been found, in accordance with the present invention, that all of the principal objects are attained by the use of a group of reagents which include broadly the N-alkylated derivatives of polyalkylene polyamines and the derivatives of such alkylated polyamines obtained by reacting them with a fatty acid acylating agent.

In accordance with the present invention we have found that while the polyalkylene polyamines themselves have no effective promoting action for acidic ore minerals, they may be readily converted into eflectlve promoters. This is accomplished by replacing at least one of the hydrogens on a terminal nitrogen with an allphatic radical of from 8 to 32 carbon atoms. One or more of the remaining hydrogens on the terminal nitrogens may be replaced by short chain alkyl or hydroxyalkyl groups. The order of making such plural substitutions is not critical. The aliphatic radical may be an alkyl group of about 8 to 32 carbons. It also may be the acyl radical of an aliphatic fatty acid of about 8 to 32 carbon atoms. However, in the latter case, at least one of the hydrogens on the other terminal nitrogen must be replaced by an alkyl or hydroxyalkyl group.

For example, a suitable compound for use as a reagent in our invention might be one represented by the following type formula:

wherein n and 3: represent small whole numbers; R is an alkyl radical of 81:0 32 carbon atoms and R R and R are hydrogen. As was noted, in a compound of this formula, either before or after the R. substitution, any or all of R, B. and ii. may be replaced by a short chain alkyl or hydroxyalkyl radical of one or two carbon atoms. Also, one or more of R R and B may be long chain alkyl radicals, possibly, but not necessarily, the same as R. Only one of R or R will have such value. c

As noted above, the long chain aliphatic radical may be an acyl radical, rather than an alkyl radical. As such, it may be the only long chain substituent in a compound of the formula:

wherein R CO is the residue of the 8 to 32 carbon atom fatty acid. R. will therefore contain '1 to 31 carbon atoms, n and :1: having the values noted above in Formula I. However, also as noted above, in such a case either R or R will be a short chain alkyl or hydroxyalkyl group or a long chain alkyl of 8 to 32 carbon atoms. The other may be, .and usually will be, hydrogen.

Depending upon the temperature conditions under which the acylating reaction is carried out, the product will be a chain compound such as that of Formula II or an imidazoline of the formula:

wherein y is zero or a small whole number and 71., RF, R and R have the values noted above with .polyamines with an alkylating agent, such as lauryl bromide, cetyl bromide, or similar alkylating agent having from about 8 to not more than about 32 carbon atoms.

The mono-, or dl-alkyl derivatives are obtained depending upon the quantity of alkylating reagent employed. In the case of the dior polyalkylated derivatives we can use more than one alkylating agent and obtain two or more different alkyl substituents. Suitable alkylating agents that may be used for producing polyalkyl derivatives of the higher alkylated polyamines include short chain aliphatic alkylating agents and other alkyiating agents such as methyl bromide, ethyl iodide, ethylene chlorohydrin, esters of chloracetic acid, esters of chlorhydrins, benzyl chloride, and the like. The following example illustrates the preparation of an N-alkyl polyalkylene polyamine; namely, N-cetyl trlethylene tetramine acetate.

Example 1 A mixture of 23 grams of cetyl bromide and 56 grams of triethylene tetramine was heated for five hours at C. in an oil bath, then cooled to room temperature when the reaction mix separated into two layers. The top layer was removed, added to 300 cc. of a 3% aqueous NaOH solution then salt added to the mix to salt out lN-cetyl triethylene tetramine as an oil. The oil was extracted from the salt solution with benzol. The benzol solution was heated to 130 C. to remove the benzol. The product, N-cetyl triethylene tetramine, was a pale amber-colored oil. One molar equivalent of acetic acid was added to the product to form the acetate which was soluble in water.

Any one of the monoor dl-alkylated compounds prepared by the foregoing method may be reacted with a fatty acid acylating agent to produce N alkylated N acylated polyalkylene polyamines. For instance, one mol of N-decyl diethylene triamine is heated to'about C. with the fatty acid equivalent of one mol vof coconut oil. The same result may be achieved by first forming the fatty acid amide by reacting one mol of diethylene triamine by heating with the fatty acid equivalent of one mol of coconut oil to 180 C. to C. and then alkylating this amide by treatment with decyl bromide.

The preparation of the reagents of the present invention is illustrated by the following examples. However, since the invention is not concerned with the method of manufacture, these examples are illustrative only and not by way of limitation.

Example 2 A mixture of '15 grams of the mono-stearoyl amide of diethylene triamine and 16 grams of anhydrousethylene chlorhydrin was heated to 190 C. under a reflux condenser until the chlorhydrin stopped refluxing, then cooled to room temperature. The product was a soft paste soluble in water. It was the hydrochloride of N- stearoyl-N'-hydroxyethyl diethylene triamine.

Emmple'3 The mono-coconut fatty acids amide of a mixture of polyethylene poiyamines (containing 50% diethylene triamine, 25% triethylene tetramine and 25% tetraethylene pentamine) was prepared by heating a mixture of 100 grams of coconut oil and 67.5 grams of the mixed polyethylene polyamines to 180 C. A mixture of '10 grams of this product and 38 grams of 2-bromo-octane was heated to 190 C. under a reflux condenser until refluxing stopped, then cooled to room temperature. The alkylated product was a soft paste,

solubleinwater. I

The alkyl-N-substituted-a-alkyl imidazolines represented by the general formula No. 3 are prepared by alkylating the reaction products of one molecule: equivalent of a polyalkylene polyamine with one molecular equivalent of a fatty acid or fatty acid ester wherein the reaction is carried out at a temperature above 250 C. In other words, when a higher fatty acid is reacted with a polyalkylene polyamine at temperature: above 250 C. two molecules of water are liberated for each mol of fatty acid resulting in the production of a ring compound. These ring compounds still have reactive hydrogens on one o: the terminal nitrogens and these hydrozens ma} such polyalkylene polyamines.

readily be replaced by any one of the alkylatlng reagents mentioned heretofore. The following speciflc illustrations describe methods for preparing specific alkyl-N-substituted- .-alkyl imidazolines. v

-5.;- Erample 4 stopped refluxing, then cooled to room temperature. The product was a soft paste soluble in water. It was the hydrochloride of N-(N'- hydroxyethyl-aminoethyl) a heptadecyl-imidazoline.

Emample5 A mixture of 70 grams of the reaction product of coconut oil and mixed polyethylene polyamines (containing 50% diethylene triamine, triethylene tetramine and 25% tetraethylene pentamine) was heated to 250 C.-270 C. and 38 grams of 2-bromo-octane was heated to 190 C.-200 C. under reflux, until refluxing stopped, then cooled to room temperature. The product (alkylateda-alkyl imidazoline) was a soft paste soluble in water.

The polyalkylene polyamines that may be em-- ployed for preparing our reagents may be represented by the following general formula:

in which n, m. and m are small numbers.

The polyalkylene polyamines of the above formula may be produced by heating an alkylene chloride with ammonia under pressure at a temperature of about Bil-120 C. When ethylene chloride is employed there is obtained a mixture of diethylene triamine, triethylene tetramine, tetraethylene pentamine, and ethylene diamine. The ethylene diamine can be removed from the mixture of the higher polyethylene polyamines by distillation. It is, of course, understood that when propylene chloride, butylene chloride, amylene chloride, and the like, are employed instead of ethylene chloride in reacting with ammonia, the corresponding polyalkylene polyamines are obtained. The expression polyalkylene polyamines employed in the claims, therefore refers to and includes any one of the polyalkylene polyamines referred to above or to a mixture of These polyamines derived from alkylene compounds are chain compounds having an amino group on each end of the chain, these terminal amino groups being separated by at least one alkyleneNH--alkylenegrouping. Illustrative formulae for some of the polyalkylene polyamines employed are as follows:

Triethylene tetramine NH CH CH NH-CH -*CH NH cH cH, NH,

Representative polyalkylene polyamines which may be employed in alkylating and condensing with fatty acids are diethylene triamine. dipropylene triamine. dibutylene triamine. triethylene tetramine. tetraethylene pentamine, or mixtures of any two or more of such polyamines either as relatively pure compounds or crude mixtures. In general they are polyamines, the diflerent amino groups of which are separated from one another by a hydrocarbon radical containing from 2 to 12 carbon atoms. The compounds used in the present invention are usually homogeneous viscous pastes which will combine with acids, such as formic, acetic. hydrochloric, and the like. to yield salts which are soluble in water. They may be used in flotation processes in the form of these watersoluble salts or the free base may be used provided satisfactory dispersion is obtained.

Either the saturated, unsaturated. or hydroxy fatty acids may be employed for reacting with the polyamines to produce the N-alkyl-Nacyl suited for froth flotation tage of this invention effect satisfactory removal of the silica but are polyalkylene polyamines, the preferred ones being those having at least nine carbon atoms, for example, lauric, palmitic, stearic, oleic, ricinolelc. capric, myristic, mixtures of such acids and especially mixtures of the fatty acids obtained from the fats and oils of either vegetable or animal sources or their glycerides such as those in coconut oil, palm oil, palm kernel oil, cottonseed oil, corn oil, linseedoil, olive oil, peanut oil, fish oils, and the like, as well as oarboxylic acids such as talloel and naphthenic acid.

While, as stated heretofore, the present invention is not limited to the treatment of any particular ore material. it has been found to be well of silica from phosphate rock and is the preferred embodiment of the invention. In the processes of removing silica from phosphate rock, the conditions are such that practically complete removal of the silica must be accomplishedin order to produce a salable phosphate material. It is therefore, an advanthat our reagents not only also economical in titles required range ore depending upon amounts used. The quanfrom 0.2 pounds per ton of the particular ore and the particular reagent. The invention is not, however, limited to such quantities.

The reagents of the present invention may be used alone or in mixtures with other promoters. They may likewise be used in conjunction with other cooperating materials such as conditioning reagents, oily or fat materials, such as hydrocarbon oils, fatty acids, or fatty acid esters.

When the reagents oi the present invention are employed as promoters in the froth flotation of silica from phosphate rock, which is the preferred embodiment thereof, the condition may be varied in accordance with procedures known to those skilled in the art. The reagent may be employed in the form of aqueous solutions, emulsions, mixtures, or solutions in organic solvents, such as alcohol and the like. The reagent may be introduced into the ore pulp prior to the actual concentration operation. They may also be stage fed into the flotation circuit.

The application of the present invention will be further illustrated in conjunction with th: following illustrations of ore beneficiation. Again it should be pointed out that these examples are by way of illustration only. All parts are by weight unless otherwise noted.

milde s:

7 Example 6 A sample of Florida. pebble phosphate was made into a fine flotation feed (--l-200 mesh) by scrubbing, polishing, and desliming until the feed was substantially slime free. This sample was divided into a number of portions, each of which successively was diluted to about 22% solids with water and treated in a Fagergren flotation machine. The particular reagent or reagent combination was added in the flotation machine, being conditioned with the pulp for three seconds without air. Air was then admitted to the machine and the resulting froth concentrate collected until the froth became barren. The test products were then dried, weighed, and assayed. The reagents used and the metallurgical results are shown in the following table.

small whole number, R is a! to 31 carbon atom aliphatic radical, the residue of an 8 to 32 cm-bon atom aliphatic fatty acid, and RF and lit are each a member of the group consisting of hydrogen,

Table Concentrate 'laillng I Lbs I at Test No. Cent Pat gist, g; or {an Insol. Cent Cent Con Cent. g, we. Insol. ML Wt. Insol.

l s4. s4 67. 47 19. 47 98.31 as as as: 1. so i) o, 50 Pine Oil 0. l2 4 54.54 are: saw cars sass an 1.14 a Me 1 Pine Oil 0.12

1 N-(N'-hydroxyethyl aminoetolgb- -he tedeoyl imldazoline hydrochloride.

'N-(N'-octylaminoethyl)- -d eoyl dssoiine hydrobromido.

The N-alkylated polyalkylene polyamines and their derivatives as used in the present invention are not used as frothers or frothing agents. Instead, they are used solely as promoters, the desired frother characteristics being obtained in the beneflciation by the use of standard frcthers such as pine oil, the cresylic acids frothers, the alcoholic frothers and the like which are commercially available. Consequently in the practice of this invention, the promoter will always be used in excess of the amount of material normally fed as a frother, i. e., in excess of about 0.10-0.12 lbs/ton of ore treated.

We claim:

1. In the beneflciation of ores containing acidic silicious minerals by floating a concentrate of the acidic silicious minerals therefrom, the improvement which comprises subjecting an aqueous pulp of the ore to agitation and aeration in the presence of at least about 0.2 lb. per ton of a collector and a relatively \small amount of a non-selective frothing agent. said collector being selected from the group consisting of those compounds represented by the formula:

a small whole number, R is a 'i to 31 carbon atom aliphatic radical, the residue of an 8 to 32 carbon atom aliphatic fatty acid, and R and R I are each a member of the group consisting of hydrogen, the short chain alkyl and hydroxyalkyl radicals of one or two carbon atoms, and the alkyl radicals of 8 to 32 carbon atoms, one of RF and B. being hydrogen.

2. In the beneflciation by froth flotation of phosphate ores containing acidic silicious gangue, the improvement which comprises subjecting a the short chain alkyl and hydroxyalkyl radicals of one or two carbon atoms, and the alkyl radicals of 8 to 32 carbon atoms, one of R and R. being hydrogen, whereby a major portion of the acidic silicious gangue is concentrated in a supernatant froth layer above the pulp.

3. In the beneflciation of low-grade phosphate ores by floating acidic silicious gangue therefrom, the improvement which comprises subjecting a pulp of the ore to froth flotation in the presence of at least about 0.2 lb. per ton of a collector and a relatively small amount of a nonselective frothing agent, said collector being a water-soluble addition salt of N-(N'-hydroxyethyl aminoethyl) a heptadecyl imidazoline, whereby a major portion of the acidic silicious gangue is concentrated in a supernatant froth layer above the pulp.

4. In the beneflciation of low-grade phosphate ores by floating acidic silicious gangue therefrom, the improvement which comprises subjecting a pulp of the ore to froth flotation in the presence of at least about 0.21b. per ton of a collector and a relatively small amount of a non-selective frothlng agent, said collector being a water-soluble addition salt of N- (N'-octyl aminoethyl) -y.- dodecyl imidazoline, whereby a major portion of the acidic silicious gangue is concentrated in a supernatant froth layer above the pulp.

DAVID W. JAYNE. HAROLD M. DAY. ELMER W. GIESEKE.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 2,200,815 Ackley May 14, 1940 2,364,272 Christmann Dec. 5, 1944 2,380,698 Jayne July 31, 1945 

1. IN THE BENEFICATION OF ORES CONTAINING ACIDIC SILICIOUS MINERALS BY FLOATING A CONCENTRATE OF THE ACIDIC SILICIOUS MINERALS THEREFROM, THE IMPROVEMENT WHICH COMPRISES SUBJECTING AN AQUEOUS PULP OF THE ORE TO AGITATION AND AERATION IN THE PRESENCE OF AT LEAST ABOUT 0.2 LB. PER TON OF A COLLECTOR AND A RELATIVELY SMALL AMOUNT OF A NON-SELECTIVE FROTHING AGENT, SAID COLLECTOR BEING SELECTED FROM THE GROUP CONSISTING OF THOSE COMPOUNDS REPRESENTED BY THE FORMULA: 